I’ve spent the past 30 minutes trying to reliably replicate this issue but I can’t find anything consistent. I’m getting content in Cards simply saying Unknown (see bottom of screen shot):
This is the card and you’ll see there’s nothing below the Button component. It’s on a global but despite it being replicated in four places, it can appear in different places on different instances.
It won’t be any help (I think) as it’s not showing up now. I saved when it happened but on opening it was back to normal. It’s happened twice but I still can’t reproduce it reliably.